Process fluid handling systems typically use pipes and valves to transport process fluids. The fluid pressures associated with process fluid handling systems often generate forces that affect the flow of the process fluids. The forces generated at one stage of a process fluid handling system may affect gases or liquids throughout the system.
The effects of the forces generated by pressurized process fluids in process fluid handling systems are often undesirable. For example, pressurized gases and liquids may accumulate large amounts of potential energy that may be dissipated as heat and noise. Conversion of accumulated potential energy to heat typically raises the temperature of the process fluid as well as the pipes, valves, etc. through which the process fluid flows, and may lead to unpredictable and undesirable behavior such as system breakdowns. Accumulated potential energy is typically released by opening valves (which release fluid pressure) in the process fluid handling system.
The release or dissipation of the potential energy stored in process fluids may also result in audible noise. Audible noise typically results when process fluid turbulence causes the process fluid to reverberate or resonate against pipe walls, valve structures, etc.
Many developments have been directed to reducing noise and other undesirable effects associated with reducing pressure and stored potential energy in process fluid handling systems. For example, one method to reduce the generation of audible noise includes insulating pipes with noise attenuating. However, pipe insulation and other methods of masking the undesirable effects of pressure and stored potential energy in process fluids do not address the cause of the undesirable effects. Nor do these methods reduce or eliminate the potentially destructive effects that the pressure and/or stored potential energy may have. Other developments include in-line apparatus that, when placed in the pipes and/or valves of a process fluid handling system, reduce or control process fluid pressures and stored potential energy as well as the undesirable effects associated therewith.
One example of a device used to reduce or control process fluid pressure build-up is a multiple stage cylindrical device described in U.S. Pat. No. 4,567,915 issued to Bates et al. The multiple stage cylindrical device described by Bates et al. includes a plurality of cylinders, each of which is press-fit inside of another cylinder and each of which has a plurality of drilled holes extending through the cylinder from an outer cylinder surface to an inner cylinder surface. Each of the cylinders of the multiple stage device disclosed by Bates et al. also has a circumferential flange at each cylinder end. When the cylinders are press-fit together, the flanges separate the cylinders so that a cavity or space is maintained between the cylinder walls. In this manner, gases or liquids flowing through the drilled holes of one cylinder may enter an open cavity between cylinders, flow through the drilled holes of a next cylinder, and then either enter another cavity between cylinders or flow outside of the multiple stage cylindrical device.
The multiple stage device disclosed by Bates et al. has several drawbacks. In particular, the device disclosed by Bates et al. is manufactured using a plurality of pre-formed cylinders. A plurality of holes is drilled into each pre-formed cylinder to enable liquids and gases and other process fluids to flow through the device. However, because the holes are drilled, the geometry of the holes is typically limited to substantially circular openings, thereby limiting the types of mechanical resistances, pressure attenuations, and noise attenuations that may be provided. Additionally, the drilling process can be a time consuming and costly process that is prone to errors and defective finished products.
A further drawback of the multiple stage device disclosed by Bates et al. is associated with the cavity or space formed between the cylinders. Specifically, little, if any, control can be imposed on the process fluid flowing in the cavities or spaces between each cylinder stage because the cavities or spaces allow relatively free (i.e., unrestricted) flow, which can result in turbulent flow patterns that generate process fluid pressure fluctuations causing audible noise, heat, etc.
An example of a multiple stage device based on a stack of substantially flat or planar rings is described in U.S. Pat. No. 5,769,122 issued to Baumann et al. The stacked-ring device disclosed by Baumann et al. uses substantially flat or planar rings having pre-cut grooves. The grooved flat rings are stacked to form a cylinder having a plurality of flow paths extending from an inner surface of the cylinder to an outer surface of the cylinder. The flow paths are formed via a plurality of complementary holes or grooves formed on the flat rings. The flow paths may be split into several paths and configured to include directional changes and obstructions. In general, the configuration of the flow paths causes a process fluid to dissipate a substantial amount of potential energy and, thus, pressure while traveling through the flow paths.
However, the stacked-ring fluid pressure reduction device disclosed by Baumann et al. is costly and time consuming to manufacture. The flat rings are typically laser cut from a large flat piece of material (i.e., flat stock). Manufacture of the flat rings often results in a relatively large amount of scrap that increases costs. Additionally, cutting each flat ring also increases the amount of time that it takes to manufacture a stacked-ring fluid pressure reduction device, which may have a significant number of flat rings (e.g., fifty stacked flat rings).
The stacked-ring fluid pressure reduction device disclosed by Baumann et al. may also be difficult to assemble. For example, several difficulties are typically encountered when stacking and joining the flat rings. In particular, the flat rings are stacked on top of each other in a predetermined orientation and then brazed together. This process is often associated with dimensional control problems such as maintaining the height and straightness of the stacked rings within a predetermined tolerance. Additionally, the performance of the joints produced by brazing is often not acceptable and leads to the production of defective parts. Still further, the orientations of the stacked rings are often difficult to control and quality issues associated with flat ring orientation often lead to time-consuming corrections or wasted material. In addition to cost, time, and manufacturing problems, some materials are often not available in sheet form to manufacture the flat rings needed to produce a stacked-ring fluid pressure reduction device.